Percutaneous transluminal angioplasty has recently become well known in the art as a delicate and artful procedure which has revolutionized medical treatment of atherosclerotic stenosis in arteries. The use of a catheter to dilate an atherosclerotic stenosis in blood vessels was first disclosed in 1964 by Dotter and Judkins. These investigators reported the development of a series of coaxial tapered dilating catheters that could be placed percutaneously through femoral artery atherosclerotic obstructions. The technique was subsequently modified by Gruntzig, who developed the balloon catheter concept. Today, balloon angioplasty is widely used to treat arterial stenosis or arterial blockages in lieu of more invasive procedures such as coronary artery bypass grafting, vascular surgery and the like.
Coronary angioplasty is now a very well known procedure. The utility of the present invention will be described in relation to coronary angioplasty although it has applications as a steering device for angioplasty of any vessel, as well as for other medical procedures involving steering a distal end of an elongated wire or strand by manipulating a proximal portion of the strand.
In the initial stages of a coronary angioplasty, a guiding catheter is inserted into the femoral artery in the groin. The guiding catheter is subsequently passed through the femoral artery into the aorta and over the aortic arch, and then maneuvered into the ostium of the coronary artery under fluoroscopic guidance. In order to dilate a coronary artery stenosis, a balloon catheter is directed through the guiding catheter and into the coronary artery until the deflated balloon is positioned across the stenosis. The balloon is then briefly inflated, thereby expanding the stenosis and relieving the blood vessel of the obstruction.
In order to guide the balloon catheter to the location of the stenosis, the balloon catheter is equipped with a guidewire which extends well beyond the distal end of the balloon catheter. The initial step in inserting the balloon catheter into the coronary artery involves advancing the guidewire beyond the guiding catheter and into the coronary artery under fluoroscopic guidance. After the guidewire is in place in the coronary artery, it is used to guide the balloon catheter into position by sliding the balloon catheter along the guidewire. In order to direct the guidewire successfully into position within the coronary artery without causing injury to the lining thereof, precise control of the guidewire is required. To provide such precise control, steering devices have been developed which allow precise rotational control of a J-tip which is generally provided at the distal end of the guidewire. Because the guidewire has extremely limited rotational flexibility, rotation of the steering device will generally result in a corresponding rotation of the J-tip. Because the guidewire must have considerable linear flexibility in spite of the need for limited rotational flexibility, workers in the field note that one may retain good control of the forward movement of the guidewire during insertion into the coronary artery by limiting the distance between the location of the steering device on the guidewire and the hub at the proximal end of the balloon catheter. If the distance between the steering device and the hub of the balloon catheter is relatively large, the control afforded the operator will be diminished because of the increased tendency for the guidewire to bend in a position between the steering device and the hub of the balloon catheter. Therefore, it is important that the distance between the steering device and the hub of the balloon catheter always be minimized. Preferably, this distance will be limited to 2-3 centimeters. Therefore, when the guidewire is being inserted into the coronary artery, the steering device must be repositioned on the guidewire as the guidewire is inserted further and further into the artery. Because this is a very delicate and artful procedure, it is very important for the operator to have as much control of the guidewire as possible. Furthermore, as the operator advances the guidewire, he or she must simultaneously watch a fluoroscopic monitor. Most operators have also found that they must hold the hub of the balloon catheter with one hand as they grasp the steering device with the other hand in order to direct the guidewire. Although the prior art steering devices which are presently available to workers in the field provide for adequate rotational control of the guidewire, it is tedious and distracting to advance the guidewire using these devices because it is necessary to use two hands to reposition them on the guidewire, and the operator's attention is necessarily diverted away from the monitor at a time when the operator needs to be particularly attentive.
The prior art steering devices generally used in the field of angioplasty today comprise a two-piece disposable plastic device having a collet-type gripping mechanism wherein a cap is screwed down over a plurality of flanges which are thereby tightened down upon the guidewire providing a tight grip thereof. Unfortunately, in order to loosen the grip of the steering device, the operator must use two hands. One hand is required to grasp the main body portion of the steering device, while the other hand unscrews the cap portion to loosen the collet-type mechanism. When the steering device is repositioned on the guidewire, both hands are again required to tighten the screw cap so that the manipulation of the guidewire may be continued. It will be appreciated that using both hands to loosen and then tighten the steering device on the guidewire every time the guidewire is advanced 2-3 centimeters can become a very tedious and cumbersome requirement.
The present invention addresses these and other problems associated with the use of a steering device for percutaneous transluminal angioplasty and related medical procedures requiring control of a guidewire or other elongated strand-like tools. The present invention also offers other advantages over the prior art and solves other problems associated therewith.